--- a/Doc/reference/simple_stmts.rst Thu Jan 12 08:06:49 2012 +0100
+++ b/Doc/reference/simple_stmts.rst Fri Jan 13 00:26:31 2012 +1000
@@ -425,10 +425,10 @@
:keyword:`finally` clause, that :keyword:`finally` clause is executed before
really leaving the function.
-In a generator function, the :keyword:`return` statement is not allowed to
-include an :token:`expression_list`. In that context, a bare :keyword:`return`
-indicates that the generator is done and will cause :exc:`StopIteration` to be
-raised.
+In a generator function, the :keyword:`return` statement indicates that the
+generator is done and will cause :exc:`StopIteration` to be raised. The returned
+value (if any) is used as an argument to construct :exc:`StopIteration` and
+becomes the :attr:`StopIteration.value` attribute.
.. _yield:
@@ -450,6 +450,7 @@
and is only used in the body of the generator function. Using a :keyword:`yield`
statement in a function definition is sufficient to cause that definition to
create a generator function instead of a normal function.
+
When a generator function is called, it returns an iterator known as a generator
iterator, or more commonly, a generator. The body of the generator function is
executed by calling the :func:`next` function on the generator repeatedly until
@@ -469,14 +470,25 @@
garbage collected), the generator-iterator's :meth:`close` method will be
called, allowing any pending :keyword:`finally` clauses to execute.
+When ``yield from expression`` is used, it treats the supplied expression as
+a subiterator, producing values from it until the underlying iterator is
+exhausted.
+
+For full details of :keyword:`yield` semantics, refer to the :ref:`yieldexpr`
+section.
+
.. seealso::
:pep:`0255` - Simple Generators
The proposal for adding generators and the :keyword:`yield` statement to Python.
:pep:`0342` - Coroutines via Enhanced Generators
- The proposal that, among other generator enhancements, proposed allowing
- :keyword:`yield` to appear inside a :keyword:`try` ... :keyword:`finally` block.
+ The proposal to enhance the API and syntax of generators, making them
+ usable as simple coroutines.
+
+ :pep:`0380` - Syntax for Delegating to a Subgenerator
+ The proposal to introduce the :token:`yield_from` syntax, making delegation
+ to sub-generators easy.
.. _raise: